Rotating electric machines are used for a wide variety of applications, such as automotive applications, aerospace applications, marine applications, industrial applications, and/or the like. Rotating electric machines include a rotor and a stator. A rotating electric machine may be an electrical motor, wherein the rotor rotates relative to the stator to convert electrical energy to mechanical energy. Rotating electric machines also include electric generators, wherein the relative rotation between the rotor and the stator converts mechanical energy to electrical energy. One example of an electric generator is an electric generator that is used onboard aircraft, such as, but not limited to, for supplying electrical power to the electrical system of the aircraft.
At least some known electric generator systems include a three-phase wound field synchronous rotating electric machine (i.e., a wound field synchronous generator). A brush-less exciter is operatively connected to the wound field synchronous generator for exciting the field winding. The brush-less exciter includes a controllable stationary direct current (DC) excitation and a three-phase rotating armature connected to a rotating rectifier that supplies the main excitation requirements of the rotating field winding of the wound field synchronous generator. Electrical power is supplied to the brush-less exciter by a pilot permanent magnet generator (PMG).
Known electric generator systems that include wound field synchronous generators are not without disadvantages. For example, the brush-less exciter and rotating rectifier of such electric generator systems may increase the cost and/or decrease the reliability of the system. Moreover, it may be difficult to sufficiently remove heat from the rotating active windings of the rotor of wound field synchronous generators, which may decrease the reliability of the system. Further, because of the rotating rectifier and active windings, wound field synchronous generators may not be suitable for use in relatively harsh environments wherein the wound field synchronous generator is exposed to relatively high temperatures, relatively low temperatures, moisture, chemicals, dust, abrasive materials, shock loading, vibration, and/or the like.